Kazimierz Kochman

Polish Academy of Sciences, Warszawa, Masovian Voivodeship, Poland

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Publications (33)59.69 Total impact

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    ABSTRACT: EGR1 and PITX1 are transcription factors required for gonadotroph cell Lhb promoter activation. To determine changes in Egr1 and Pitx1 mRNA levels in central and peripheral pituitary stimulations, an in vivo model based on intracerebroventricular (i.c.v.) pulsatile (1 pulse/0.5 h over 2 h) GnRH agonist (1.5 nM buserelin) or antagonist (2 nM antide) microinjections was used. The microinjections were given to ovariectomised and 17B-estradiol (3 × 20 μg), ERA agonist PPT (3 × 0.5 mg), ERB agonist DPN (3 × 0.5 mg) subcutaneous pre-treated rats 30 min after last pulse anterior pituitaries were excised. Relative mRNA expression was determined by quantitative reverse transcription polymerase chain reaction. Results revealed a gene-specific response for GnRH and/or oestrogenic stimulations in vivo. Buserelin pulses enhanced Egr1 expression by 66% in ovariectomised rats, whereas the estradiol-supplemented+i.c.v. NaCl-microinjected group showed a 50% increase of Egr1 mRNA. The oestrogenic signal was transmitted via ERA and ERB activation since PPT administration resulted in 97% and DPN in 62% elevation of Egr1 mRNA. A synergistic action of GnRH agonist and 17B-estradiol stimulation of the Egr1 gene transcription in vivo was found. GnRHR activity did not affect Pitx1 mRNA expression; regardless of NaCl, buserelin or antide i.c.v. pulses, subcutaneous oestrogenic supplementation (with 17B-estradiol, PPT or DPN) consistently decreased (by -46%, -48%, and -41%, respectively) the Pitx1 mRNA in the anterior pituitary gland. Orchestrated Egr1 and Pitx1 activity depending on specific central and peripheral regulatory inputs could be responsible for physiologically variable Lhb gene promoter activation in vivo.
    Journal of Molecular Endocrinology 09/2014; · 3.58 Impact Factor
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    ABSTRACT: The amount of decapeptide decapeptide gonadoliberin (GnRH) that reaches pituitary gland depends not only on transcriptional, translational and posttranslatonal processes but also on the extent of degradation exerted by specific proteolytic enzymes. The copper-gonadoliberin (Cu-GnRH) complex preserves the native GnRH amino acid sequence but contains Cu(2+) ion bound to the nitrogen atom at the imidazole ring of the His(2). The aim of this study was to determine whether GnRH and Cu-GnRH molecules differ in their susceptibility to proteolysis in male rat hypothalamic and pituitary tissue in vitro. RIA was applied for a time-dependent study based on 0-90 min incubations at 30°C of exogenous peptide (2.5 μg GnRH or Cu-GnRH) in respective hypothalamic/pituitary supernatant and pellet fractions. To compare the protective effect of bacitracin, a competitive PEP inhibitor, incubations were made with (125 μg/sample) or without an inhibitor. In the second experiment 100 μg of GnRH or Cu-GnRH were incubated for 5 h at 37°C in hypothalamic and pituitary tissue in vitro and then HPLC analysis was applied both to characterize the elution pattern of GnRH and Cu-GnRH degradation products as well as to determine their AA composition. In both tissues, Cu-GnRH remained more resistant to enzymatic degradation and fully protected in the presence of bacitracin. In conclusion, the obtained data suggest that copper ion changed GnRH conformation and significantly modified its physiological properties due to a hindered endopeptidases access to specific AA bonds. Therefore, the Cu-GnRH complex might be considered as GnRH analog potentially able to prolong the occupation of a GnRH receptor at the gonadotrope cells.
    Journal of physiology and pharmacology: an official journal of the Polish Physiological Society 02/2012; 63(1):69-75. · 2.48 Impact Factor
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    ABSTRACT: Valproate (VPA) a potent antiepileptic drug has been claimed to induce reproductive disturbances in men. Long-term VPA treatment can affect sperm morphology and induce testicular atrophy in non-epileptic rats. It has been reported that VPA reduced testosterone secretion stimulated by hCG in isolated rat Leydig cells. These results suggest direct effect of VPA on testes in rats. However centrally mediated effects at hypothalamo-pituitary level can therefore not be excluded. This study focused on the dose and time-dependent effects of VPA on basal and GnRH-induced LH and FSH release from the primary anterior pituitary cells culture of male rats. The dose-dependent effect of 10 nM-100 mM of VPA on basal LH release from anterior pituitary cells after 3h of incubation was examined. To determine the time-dependent effects on LH, FSH, TSH and PRL release short (3 h) and long-term (24 h) incubations in the presence of 10 nM, 100 nM and 1 μM of VPA were maintained.To assess whether VPA can affect GnRH-induced LH and FSH release, cells were incubated for 3 h with 10 nM, 100 nM and 1 μM of VPA in the presence of GnRH. The concentration of rLH, rFSH, rPRL and rTSH in incubation medium was determined by RIA method. VPA did not affect the basal LH, FSH, PRL and TSH release from the primary anterior pituitary cells culture of male rats. VPA in concentration 1µM significantly suppressed GnRH-induced LH secretion. However VPA at all tested doses diminished GnRH-induced FSH release. VPA may diminish gonadotropin release in vitro but this effect can only be achieved after GnRH-dependent specific receptor activation. Both gonadotropins differ in their pattern of response for increasing doses of VPA.
    Neuro endocrinology letters 04/2011; 32(2):206-11. · 0.93 Impact Factor
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    K Kochman, M Czauderna
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    ABSTRACT: The necessity of appropriate nutrition with diets containing omega-3 and omega-6 fatty acids for physiologically optimal brain and nervous tissue function has been demonstrated in numerous experiments conducted in very prestigious research laboratories worldwide. Complex mechanisms and dysfunctions in the area of developmental neurobiology and neurology are impossible to understand and describe in detail without the interdisciplinary study of diet and nutrition. Studies of human infants suggest that dietary docosahexaenoic acid plays an important role in cognitive development and, in cases of its deficit, in some neurodevelopmental disorders as well; this possibility has important public health implications. Both omega-3 and omega-6 fatty acids are crucial elements in the structure and function of cellular membranes, determining their proper physiological activity in regards to fluidity, intracellular transport, and protection against intruders such as bacteria and viruses. These acids actively participate in the biosynthesis of such neurotransmitters as dopamine and serotonin, which are required in nerve cells for quick and efficient signal conductance. The proper content of omega-3 fatty acids in diets increases and improves learning ability, problem-solving skills, concentration, memory, and communication between nerve cells. Omega-3 fatty acids also support positive mood and emotional balance, and are beneficial in the treatment of depression and Alzheimer's disease; they also help maintain good mental skills in aging people. Omega-3 fatty acids are derived from food; they are able to restore the proper flexibility of neuronal membranes, resulting in improved cell communication and physiologically optimal brain function in cases in which this flexibility was previously disordered.
    Journal of Animal and Feed Sciences 01/2010; 19:511-524. · 0.76 Impact Factor
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    ABSTRACT: The recent genetics and molecular biology progress seems to be a fascinating challenge for the interdisciplinary studies on the effects of genetic changes in gene structure that causes the modification of physiological functions of many important proteins including hormones. Pig prolactin is one of the interesting hormones for this study. The aim of the study was to analyze the mutation in 5'UTR region of the pig prolactin (PRL) gene and to evaluate the effect of this polymorphism on changes in plasma prolactin concentration. It was found that only two individual groups of animals differed by the genotype in examined PRL gene locus - homozygote C/C and heterozygote C/T. PRL plasma concentration was 38.4 ng/ml (for C/T animals) or 42.7 ng/ml (for C/C animals). Animals with C/C genotyped exhibited a tendency to elevate PRL concentration as compared to the C/T group (p< 0.07). This research combines the genetic, molecular and, in vivo, physiological study which allows focus on the possible relationship between the gene polymorphism and physiological status of animal.
    Neuro endocrinology letters 07/2009; 30(2):221-6. · 0.93 Impact Factor
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    ABSTRACT: A progressive decrease in body weight and retarded linear growth observed in mosaic male mice with the mutation linked to X-chromosome (Atp7a(mo-ms)) raised the question whether hypophysiotropic growth axis activity may be affected in these animals. A pathologically developed median eminence ultrastructure with very low somatostatin accumulation as well as an intensive phagocytosis of growth hormone cells observed in the anterior pituitary gland raised the question whether hypothalamic growth hormone-releasing hormone (GHRH) neuronal network is also affected in mosaic mice. In this study an arcuate nucleus GHRH neurons ultrastructure as well as GHRH peptide accumulation in normal and mutant mice were compared. An electron microscopic immunocytochemical method with colloidal-gold labeling was applied to compare the ultrastructural morphology of GHRH neuron and intracellular GHRH peptide distribution. Mosaic mice exhibited a pathologically developed ultrastructure of arcuate nucleus GHRH neurons, defective intracellular peptide localization as well as reduced peptide storage. Obtained results support the crucial role of unaltered copper metabolism in physiological development of hypophysiotropic growth axis activity. Consequently, a pathologically developed GHRH hypothalamic network may impact progressive decrease in body weight and retarded length growth observed in mosaic male mice.
    Brain research bulletin 05/2009; 80(3):128-32. · 2.18 Impact Factor
  • Kazimierz Kochman, Alina Gajewska, Krzysztof Bieniarz
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    ABSTRACT: Receptor binding of GnRH is connected with the stimulation of pituitary gonadotropic cells leading to both the release and biosynthesis of gonadotropins. The binding is connected with the conformational changes in the receptor which induce the specific intracellular signalisation. The study of fish GnRHs and their receptors may give us new knowledge of the complex interplay of different mechanisms involved in neuroendocrine regulation of reproduction. Receptor binding of both mGnRH and sGnRH were compared by the study utilizing the displacement method with mGnRH or sGnRH as radioactive tracers. Incubation was performed at 2 degrees C to avoid ligand degradation. The comparative binding of mGnRH and sGnRH with GnRH receptors from the female rat pituitary and female carp pituitary was studied. At the 50% of displacement, the binding of sGnRH to the rat pituitary receptor was very small and in comparison to the binding of mGnRH (100%) was in the range 2-15%. However, the binding of mGnRH to carp pituitary receptors is small in comparison with the binding of sGnRH (100%) and was in the range 5-20%. The results demonstrated the differences in binding of different GnRHs to the receptor in rats and carp. This suggests that the structures of GnRH and its receptor undergo co-evolution in different classes of animals.
    Neuro endocrinology letters 03/2009; 30(1):139-43. · 0.93 Impact Factor
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    ABSTRACT: Polymorphisms in the bovine ghr and igf1 genes. Ghr and igf1 genes have been associated with milk and meat production of cattle. However, the molecular and physiological mechanisms underlying such associations are unknown. The objective of this study was to examine the effects of polymorphisms in 5'-regions of the bovine ghr and igf1 genes on the igf1 gene expression in the liver and on the level of IGF1 in blood of Polish Holstein-Friesian cattle. Individual and combined effects of single nucleotide polymorphisms (SNPs) in the 5'noncoding regions of the bovine igf1 and ghr genes on the IGF1 level in blood and igf1 gene expression in liver were examined. One SNP in the igf1 gene and four SNPs in the ghr gene were analyzed. IGF1 level in blood was measured by radioimmunoassay (RIA) in 211 heifers and bulls of Polish Holstein-Friesian cattle (of Black-and-White type). The igf1 gene expression was measured in livers of bulls carrying different igf1 and ghr genotypes (from three to nine animals per genotype) using real-time reverse transcription-PCR methods with the gapdh gene as a reference. We showed that C/T transition in the promoter region of the igf1 gene influences the gene expression; relative igf1 expression was higher for animals with the CC genotype than for those with the TT and CT genotypes. TESS analysis showed that C/T transition in the igf1 gene co-localizes with the NF1 transcription factor binding site. Also, the ghr genotype appeared to significantly influence the igf1 gene expression in the liver, and we found the highest expression for the genotypes: RFLP-AluI (AT), RFLP-Fnu4HI(CC), and RFLP-NsiI(GA), and for the combined ghr genotype: AluI(AT)/ Fnu4HI(CC)/NsiI(GA). We discovered a significant association between the igf1 genotype and the IGF1 blood level. The highest IGF1 content in blood serum was found in CC genotype animals (1024 ng/ml) vs 698 ng/m and 859 ng/min in the TT and CT igf1 genotypes, respectively. Moreover, we noticed significant differences between ghr genotypes. The highest blood levels of IGF1 were for the animals carrying the ghr genotypes: RFLP-AluI(AA), RFLP-Fnu4HI(CC), and RFLP-NsiI(AG). Ghr haplotypes also significantly affected the IGF1 blood level. Animals of the combined ghr genotypes AluI(AA)/AccI(CC)/Fnu4HI(CC)/NsiI(AG) and AluI(AA)/AccI(CT)/Fnu4HI (CC)/ NsiI(AG) had a higher IGF1 concentration in blood than other genotype carriers. The present results indicate that the effects of polymorphism in the igf1 and ghr genes on cattle milk or meat production traits could be at least partially mediated through their effects on the igf1 gene expression in the liver and the IGF1 level in blood.
    Neuro endocrinology letters 01/2009; 29(6):981-9. · 0.93 Impact Factor
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    ABSTRACT: Neural control of the anterior pituitary function consists of the interplay of neuropeptides action, gonadal steroid hormones and many other factors. The physiological effect of this regulatory action is the release and synthesis of protein hormones in the precise time and quantity. The main factor responsible for the gonadotropins release and synthesis is the gonadotropin-releasing hormone (GnRH). We must still study the modulation of the synthesis of the gonadotropins subunits - LHbeta, FSHbeta and alpha subunit by different forms of GnRH and by its analogs, in order to better understand the regulation of gonadotropin release and synthesis. THE AIM of this study was to develop real-time PCR assays of five candidate reference genes for normalization purposes in order to quantify target transcripts in anterior pituitary cells during the preovulatory period. Moreover, we focused on the influence of GnRH receptor antagonist (antide) treatment on mRNA expression levels of GPalpha, LHbeta, FSHbeta, FST(follistatin) and PRL(prolactin) genes in these cells. Anterior pituitary cells were obtained from pituitary glands of four mature pigs at the preovulatory phase. Cells were incubated with or without antide and relative mRNA level of target genes was measured using the Applied Biosystems 7500 Real Time System. For an exact comparison of mRNA quantity, the stability of five reference genes, ACTB, B2M, GAPDH, RPL1, and TOP2B was evaluated to choose the most appropriate reference gene for qRT-PCR normalization in the pituitary cells. Expression stability of reference genes was calculated using the geNorm application. The developed method of PCR assay was applied to study gene expression in pig pituitary cells in short culture. The most stably expressed genes in the pituitary cells were GAPDH and TOP2B. The expression of ACTB, B2M and RPL1 appeared to be highly unstable. After normalization to the GAPDH/TOP2B, results showed that the mRNA expression of the FSHbeta gene was highest in comparison with LHbeta, GPalpha, FST and PRL genes (p<0.005). Pre-treatment of cells by the antide resulted in lower mRNA expression of these genes, while FSHbeta mRNA had a significantly lower expression (p<0.05) in comparison with control. Real-time PCR analysis of the expression of LHbeta, FSHbeta, alpha subunit, follistatin and prolactin genes in porcine anterior pituitary cells during the preovulatory period is suitable for the study of modulatory action of metal complexes with GnRH on the expression of these genes.
    Neuro endocrinology letters 12/2008; 29(6):958-64. · 0.93 Impact Factor
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    Anna Michaluk, Kazimierz Kochman
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    ABSTRACT: Copper (Cu) is one of the essential trace metals which are necessary in maintaining the functioning of living organisms. The current knowledge on the role of copper in animal reproduction is presented in the article. Our studies have shown that complexes of copper (Cu²+) with gonadotropin-releasing hormone (GnRH) are even more effective in the release of LH than native GnRH. Moreover, Cu-GnRH is more potent in inducing in vivo release of FSH than LH. Copper complexes with GnRH interact with GnRH receptors (GnRHR) and modulate intracellular signaling in the gonadotrope cells of the anterior pituitary. Copper plays also a significant role in maintaining normal fetus development in mammals.
    Reproductive biology 12/2007; 7(3):193-205. · 1.22 Impact Factor
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    ABSTRACT: Nucleotide sequence polymorphisms in the coding gene regions may influence the biological properties of proteins encoded by a gene. The A/T substitution in exon 8 of the growth hormone receptor (GHR) gene results in changed amino acid sequence 279 (Phe/Tyr) in the transmembrane domain of the receptor protein and therefore could influence its functional parameters. We searched for the relationship between the A/T nucleotide polymorphism in the GHR gene the receptor binding capacity and dissociation constant. Nucleotide sequence variations in the exon 8 (coding for the transmembrane domain of the receptor) of the bovine GHR gene and in fragments of adjacent introns were analysed using PCR-SSCP and sequencing techniques. GH receptor binding capacity (Bmax) and dissociation constant (Kd) for GHR were determined by the Scatchard analysis in livers of ten bulls carrying the AA or AT GHR genotypes. Two single nucleotide polymorphisms (SNPs) were identified--the C/T transition in intron 8 at position 863+32 and the A/T transversion in exon 8 at position 836, the latter resulting in Phe/Tyr amino acid substitution in the receptor protein. The results showed significant differences in the GHR binding capacity between these genotypes. Bmax was significantly greater (p< or =0.01) in bulls carrying TT genotype of GHR in comparison to those with the AT genotype. No significant differences in the dissociation constants (Kd) were found. Our results demonstrated that single base substitution in the transmembrane domain encoding region of GH receptor gene may influence the physiological properties of the receptor.
    Neuro endocrinology letters 08/2007; 28(4):401-5. · 0.93 Impact Factor
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    ABSTRACT: The present studies were undertaken to examine the effect of copper and nickel salts and their complexes with GnRH on LH release from the pig anterior pituitary cells in vitro. The potency of Cu-GnRH and Ni-GnRH binding to GnRH receptors with iodinated GnRH as a radioactive tracer was also verified. The incubation of pig pituitary cells with Cu and Ni acetate salts showed no effect of the studied ions on LH release at any concentration used. However, nickel salt at a lower dose (10(-10) and 10(-9) M) tended to decrease LH output. By contrast, the native GnRH as well as its metal complexes significantly stimulated LH release after three hours of treatment and Cu-GnRH was found to be the most effective. The results showed that Cu and Ni complexes with GnRH but not their acetate salts are effective in LH release from pig pituitary cells collected from adult female pigs.
    Neuro endocrinology letters 09/2006; 27(4):483-6. · 0.93 Impact Factor
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    ABSTRACT: An electron microscopy immunocytochemical study was performed to determine the expression pattern of growth hormone (GH) in mosaic mutant mice adenohypophysis. In normal condition GH was restricted to the secretory granules of all growth hormone cells. Mosaic mice adenohypophysis contained growth hormone cells which have distinctive GH labeled secretory granules at the level seen in control animals. Ultrastructurally, some GH cells of mosaic mice presented abnormalities, but labeling intensity of secretory granules in these cells was always comparable to the basal condition. The striking findings presence of two forms (simple and activated) of folliculo-stellate cells (FS) in close association trough gap or tight junction with GH cells localized especially near the perivascular space. Frequently, in cytoplasm of FS cells, large clusters containing fragments of GH labeled cell were present. Additionally, the existence of large intracellular, electron-lucent spaces, with remnant cellular material in parenchyma of mosaic mutant mice adenohypophysis could suggest intensive process of GH-cell destruction. Our electron microscopy immunocytochemical results provide evidence for loss of GH cells in mosaic mice by phagocytosis. We suppose that impaired body growth observed in mosaic mutant male rats may be, at least partially, a consequence of an alteration in somatotropic axis activity. Loss of GH cells in mosaic mice by phagocytosis supported by FS cells may contribute to this effect.
    Brain Research Bulletin 07/2006; 70(1):94-8. · 2.94 Impact Factor
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    ABSTRACT: Leptin is a polypeptide that plays a key role in the regulation of energy homeostasis and is also linked, among others, to mechanisms controlling reproductive processes. Data concerning the involvement of leptin in controlling reproductive functions at the level of hypothalamus and pituitary in the pig are limited. Therefore, in the present study, an expression of genes coding for leptin and long-form leptin receptor (Ob-Rb) was determined by a semiquantitative reverse transcription polymerase chain reaction (RT-PCR) in the discrete areas of porcine hypothalamus (medial basal hypothalamus - MBH, preoptic area - POA, stalk median eminence - SME) and pituitary (anterior - AP and posterior/neural - NP parts) during the luteal phase of the cycle (days 10-12 and 14-16) and two early stages of pregnancy (days 14-16 and 30-32). Leptin gene expression in MBH was found to be higher in the mid- than in the late-luteal phase, whereas in other structures studied it remained unchanged during these periods. More pronounced differences were noted in expression of Ob-Rb gene, which was increased in MBH, AP and NP during the late-luteal phase in comparison to the mid-luteal one, whilst the relationship in the POA was reversed. In turn, during pregnancy, leptin gene expression in all tested areas of hypothalamus as well as Ob-Rb mRNA content in MBH were higher on days 30-32 than on days 14-16. In contrast, in the anterior pituitary, Ob-Rb gene expression was more pronounced on days 14-16 than during later stage of pregnancy. Comparison of leptin and Ob-Rb mRNA content in studied structures between the mid-luteal phase and days 14-16 of pregnancy revealed inhibition of leptin gene expression in almost all examined tissues (MBH, POA, SME, NP) during early pregnancy whereas Ob-Rb gene expression was inhibited in POA but stimulated in both parts of the pituitary during this stage. In summary, obtained results suggest an involvement of leptin in the regulation of hypothalamic-pituitary axis activity during both the luteal phase of the cycle and early pregnancy in pigs.
    Journal of physiology and pharmacology: an official journal of the Polish Physiological Society 04/2006; 57(1):95-108. · 2.48 Impact Factor
  • Alina Gajewska, Ewa Wolińska-Witort, Kazimierz Kochman
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    ABSTRACT: The direct monosynaptic pathway which exists between vasoactive intestinal peptide (VIP) and GnRH neurons in the hypothalamic preoptic area provides a neuroanatomical background for the modulatory effects of VIP exerted on GnRH neurons activity. Though central microinjection of VIP revealed its involvement in the modulation of LH release pattern, there is a lack of data concerning a possible VIP influence on the alpha and LHbeta subunit gene expression in the pituitary gland. Using a model based on intracerebroventricular pulsatile peptide(s) microinjections (1 pulse/h [10 microl/5 min] over 5 h) the effect of exogenous VIP (5 nM dose) microinjection on subunits mRNA content in ovariectomized/oestrogen-pretreated rats was studied. Subsequently, to obtain data concerning the involvement of GnRH and VIP receptor(s) in the regulation of alpha and LHbeta subunit mRNA expression, OVX/estrogen-primed rats received a pulsatile microinjections of 5 nM VIP with 3 nM antide (GnRH receptor antagonist) or 5 nM VIP with 15 nM VIP 6-28 (VIP receptor antagonist). In this case, substances were given separately with a 30 min lag according to which each antagonist pulse preceded a VIP pulse. Northern-blot analysis revealed that VIP microinjection resulted in a decreased alpha and LHbeta mRNA content in pituitary gland and this effect was dependent on GnRH receptor activity. Moreover, obtained results indicated that centrally administered VIP might operate through its own receptor(s) because a receptor antagonist, VIP 6-28, blocked the inhibitory effect of VIP exerted on both LH subunit mRNA content and LH release.
    Brain Research Bulletin 11/2005; 67(4):319-26. · 2.94 Impact Factor
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    ABSTRACT: The aim of this study was the detection and location of long form leptin receptor (OB-Rb) in different area of hypothalamus and pituitary in the pig during early pregnancy. Expression of OB-Rb was examined by RT-PCR in the different area of hypothalamus: medial basal hypothalamus (MBH), preoptic area (POA), stalk median eminence (SME), as well as pituitary: the anterior (AP) and posterior (NP) lobe collected from gilts at days 14-16 (n=4) and 30-32 (n=4) of pregnancy. The results showed that OB-Rb mRNA was expressed in the hypothalamus (MBH, POA and SME), pituitary (AP, NP) and adipose tissue in the pig during early pregnancy (at days 14-16 and 30-32). These findings support the idea that leptin might play a role in the regulation of the hypothalamic-pituitary axis activity, and consequently in the control of pregnancy during critical period of embryo implantation in the pig.
    Neuro endocrinology letters 09/2005; 26(4):305-9. · 0.93 Impact Factor
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    ABSTRACT: Gonadotropin releasing hormone (GnRH) is an essential factor in the regulation of synthesis and release of pituitary gonadotropins. After binding to specific receptors and coupling with G proteins, it triggers the intracellular signaling involving the synthesis of inositol phosphates and diacylglycerol. Previously we have showed that certain metal complexes with GnRH, i.e. copper (Cu-GnRH) and nickel (Ni-GnRH) are able to bind to the GnRH receptors. The intracellular signalling of these complexes, however, has not been yet elucidated. In this experiment, the ability of the Cu-GnRH and Ni-GnRH complexes to modulate cAMP synthesis and phosphoinositols formation in the pig anterior pituitary cells in vitro was studied. The native GnRH and its metal complexes stimulated the luteinizing hormone (LH) release, but only the effect of Cu-GnRH was found to be a dose-dependent. The metal complexes did not significantly influence inositol phosphates accumulation, while their effect on cAMP synthesis was significantly more potent than that of GnRH alone. We conclude that the Cu-GnRH and Ni-GnRH complexes increase LH release in the porcine pituitary cells although their intracellular signaling is different from that of the native GnRH. It seems that metal complexes with GnRH deserve more attention in further studies.
    Neuro endocrinology letters 09/2005; 26(4):377-82. · 0.93 Impact Factor
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    ABSTRACT: MALDI-TOF mass spectrometry, 1H NMR spectrometry, the continuous variation method and molecular modeling by MM3 calculation confirmed our earlier studies showing that gonadotropin-releasing hormone (GnRH) forms complex with copper(II) ion with the binding ratio 1:1. The copper(II) complex formed at physiological pH has a square planar configuration and GnRH complexes with nickel(II) and cobalt(II) ions are less stable than that of copper(II).
    Neuro endocrinology letters 07/2005; 26(3):247-52. · 0.93 Impact Factor
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    ABSTRACT: Metal complexes with GnRH were shown to interact with GnRH receptors in pituitary cells. In the present study we examined the effects of GnRH and its cobalt complex form (Co-GnRH) on LH secretion and generation of second messengers, namely inositol phosphates (IPs) and cAMP, in porcine pituitary cells in vitro. The cells were obtained from gilt pituitary at the pre-ovulatory phase of estrous cycle and cultured for 72 h before challenge with GnRH or Co-GnRH. Both substances induced a significant increase in LH release that was detectable after 60 min (P<0.05) of treatment, with the Co-GnRH complex being more efficient than GnRH at 180 min (P<0.01). GnRH and Co-GnRH were equally effective at 10(-8)M (P<0.01), however, at the lowest (10(-9)M) as well as the highest (10(-7)M) concentrations tested, Co-GnRH was more potent than its native counterpart (P<0.01). Interestingly, Co-GnRH revealed twice more efficient than GnRH at stimulating cAMP production, an effect which was detectable in cells after 1h-incubation (P<0.001). In contrast, while native GnRH induced a rapid increase (P<0.05) in IPs no such effect of Co-GnRH was observed. These data demonstrate that Co-GnRH and GnRH differentially effect on the signaling pathway in porcine gonadotropes and suggest that in these cells, the releasing action of Co-GnRH results from the mediation via the cAMP/protein kinase A second messenger system.
    Brain Research Bulletin 05/2005; 65(5):391-6. · 2.94 Impact Factor
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    ABSTRACT: Although galanin, which exerts its effects both at the hypothalamic and pituitary level, has been implicated as an important neuroendocrine regulator of hypothalamic-pituitary-gonadal axis activity, there is a lack of data concerning its involvement in the regulation of gonadotropin subunit gene expression. To elucidate whether galanin can influence luteinizing hormone (LH) subunit mRNA content, as well as affect gonadotropin-releasing hormone (GnRH) receptor activity, a model based on pulsatile (one pulse per hour over 5 h) galanin (1 nM) microinjections directly into the third cerebral ventricle of ovariectomized (OVX) and/or oestrogen/progesterone-pretreated rats was used. Furthermore, to determine galanin effects on GnRH-induced LH subunit mRNA synthesis, a cocktail of 1 nM GnRH and 1 nM galanin was coadministered in a pulsatile manner to OVX/steroid primed rats. Subsequently, to obtain data concerning the role of galanin receptors in the regulation of pituitary alpha (common to LH, follicle-stimulating hormone, thyroid-stimulating hormone) and LHbeta subunit gene expression, OVX/oestrogen/progesterone rats received microinjections of 1 nM of the receptor antagonist galantide and 1 nM of galanin. In this case, both substances were administered separately, with a 30 min lag, according to which each galantide pulse always preceded a galanin pulse. Northern-blot analysis revealed that intracerebroventricular pulsatile galanin injections were effective in stimulation of both alpha and LHbeta subunit mRNA levels and that this effect was apparently steroid-dependent. Moreover, galanin also up-regulated GnRH receptor functional parameters (affinity and maximum binding capacity) but was ineffective in potentiating GnRH-induced accumulation of both subunit mRNAs. The results from the study also indicate that galanin acts through its own receptor(s) because a receptor antagonist, galantide, significantly reduced the stimulatory effect exerted by galanin on the expression of both LH subunit genes in vivo.
    Journal of Neuroendocrinology 07/2004; 16(6):558-65. · 3.51 Impact Factor

Publication Stats

115 Citations
59.69 Total Impact Points

Institutions

  • 1992–2014
    • Polish Academy of Sciences
      • • The Kielanowski Institute of Animal Physiology and Nutrition
      • • Instytut Genetyki i Hodowli Zwierząt
      • • Zakład Farmakologii Doświadczalnej
      Warszawa, Masovian Voivodeship, Poland
  • 2005
    • Institute of Animal Reproduction and Food Research of Polish Academy of Sciences
      • Institute of Animal Reproduction and Food Research
      Allenstein, Warmian-Masurian Voivodeship, Poland
    • National Institute of Advanced Industrial Science and Technology
      Tsukuba, Ibaraki, Japan
  • 1987
    • University of Warsaw
      • Department of Animal Physiology
      Warsaw, Masovian Voivodeship, Poland